The capability of a mobile robot to travel over a wide range of terrains with minimal human interference and control, and even autonomously, is a concern for mobile robots. This is particularly true for robots that are for intended for use in unknown terrains and in a wide range of terrains. A related issue for mobile robots is to provide a robot that can be in-field repaired and maintained.
The majority of current mobile robot platforms are either wheel or track-based. Wheels are suitable for motion over smooth, plain terrain at high speed, whereas tracks are suitable for motion over unstructured terrain, stairs, and ditches at slow speed. The problem in most practical circumstances is that it may be beneficial to switch intermittently between wheels and tracks. If the terrain is unknown or unstructured, or there is a security mission in an urban setting that involves flat terrain (street) and stairs, a wheeled robot may be unsuitable and a tracked robot may be too slow if the distance to travel is large.
Some mobile robots provide manually reconfigurable track-wheeled locomotion thus offering the advantages of both types of systems; however there are limitations. Manually reconfigurable track-wheeled mobile robots require manual conversion from wheel or track configurations and vice-versa, as only one option of mobility can be used at a time. Examples of these are found in US patent application publication number 2009/0266628A1 to Schempf et al., published on Oct. 29, 2009. The inherent limitation in the use of such manually reconfigurable track-wheeled mobile robots is that the terrain must be known a priori for the operator to select one system or the other at the appropriate time during the mission.
In the case of tracked robots it is known that adding a pair of tracked flippers pivotally attached to both sides of the chassis at one or both ends or at the center of the chassis' side panels enhances the ability of the mobile robot to maneuver stairs and overcome obstacles, as shown in U.S. Pat. No. 6,263,989 issued to Won on Jul. 24, 2001 and U.S. Pat. No. 7,493,976 issued to Goldenberg et al. on Feb. 24, 2009. These robots provide remote controlled variable configuration articulated tracked vehicles to ease overcoming obstacles.
Another approach is with concurrent operation of tracks and wheels. However there are some limitations in this approach due to wheel interference while overcoming obstacles in the track mode and additional loading due to tracks in the wheel mode. Examples of this approach are shown in U.S. Pat. No. 5,022,812 issued to Coughlan et al. on Jun. 11, 1991 and in US patent application publication number 2008/0258550 to Webster et al. and published on Oct. 23, 2008.
Another approach is to run the robot on tracks, and then attach wheels on the pulleys' shafts converting the robot to wheeled, and vice-versa. However, this can only be done manually, not from a distance or autonomously.
However, all of these approaches have some limitations. Accordingly it would be advantageous to provide a dual mode mobile robot that can be easily changed remotely or autonomously from one mode to another and operates well in each mode.